There are many known transmission mechanisms that comprise a cone clutch whereby a drive member such as a gear can either be coupled with a rotatable shaft for rotation with it or uncoupled from the shaft for rotation relative to it. In most mechanisms of this type, the cone clutch comprises at least one clutch element that has a splined connection with the shaft and has a conical surface concentric with the shaft. The drive member is rotatably mounted either on the shaft itself or on some other journal that is concentric with the shaft, and in either case it has a concentric conical surface which mates with the conical surface on the clutch element. For constraining the drive member to rotate with the shaft, the clutch element is shifted axially along the shaft to a position in which the conical surfaces are engaged under bias. Shifting the clutch element axially through a small distance away from this position disengages the conical surfaces and frees the drive member for rotation relative to the shaft. In some such mechanisms there are two clutch elements, located at axially opposite sides of the drive member or of an intermediate member that is confined to coaxial rotation with the drive member, and each clutch element has a conical surface that cooperates with one of a pair of mating conical surfaces on the drive member or on the intermediate member.
In all of these mechanisms the drive member and the clutch element or clutch elements have been mounted axially adjacent to one another, and usually, too, the mechanism further included an actuator on the shaft for effecting clutch element shifting to provide for coupling and uncoupling the drive member. Thus, the mechanism was relatively bulky, in that it extended through a substantial distance along the shaft. In addition, it was necessary to provide bearings on which the drive member was mounted for its rotation relative to the shaft and by which it was confined against axial displacement, and these were relatively expensive.